Scanned from 9 x 9 contact prints (nominal scale ca. 1:20,000) on Crosfield Celsis 6200 drum scanning system at 750 dpi. Quality assurance target not published but available by contacting the Illinois State Library Map Dept. MrSID files compressed at a target ratio of 6:1. Uncompressed TIFF images on cd available from the Illinois State Library Map Dept.

Relation.Requires

Mode of access: World Wide Web. System requirements: Plug-in or image viewer, ExpressView Browser plug-in available for download. System requirements for interactive map: Internet Explorer best, frames and JavaScript enabled.